Cathodoluminescence Study of Damage Formation and Recovery in Si-ion-implanted β-Ga2O3

Ion implantation and activation annealing are key processes in the creation of an ideal free carrier distribution in semiconductor devices. Ultra-wide-bandgap (UWBG) semiconductors, such as gallium oxide (Ga 2 O 3 ) and aluminum nitride (AlN), have many advantages suitable for power-device applications. We implanted silicon (Si) at doses ranging from 1 \times 10^{11} to 1 \times 10^{15} \mathrm{~cm}^{-2} into \beta-\mathrm{Ga}_2 \mathrm{O}_3 (−201) wafers, and annealed them at 800 and 1000° C in N 2 atmosphere. Secondary ion mass spectrometry (SIMS) and cathodoluminescence (CL) were used to evaluate the dopant profile and damage resulting from ion implantation. The CL intensity decreased rapidly with the dose. Even at a dose of 1 \times 10^{11} \mathrm{~cm}^{-2} , the intensity dropped by nearly half of its value for the bare wafer. The CL intensity recovered after annealing at all doses; however, the CL intensity did not fully recover even after annealing at 1000°C. Moreover, the CL-depth profile at a dose of 1 \times 10^{15} \mathrm{~cm}^{-2} after annealing at 1000°C showed pronounced intensity decay near the Si-diffused region. The CL-intensity decay was strongly correlated with Si diffusion. This phenomenon suggests that high-temperature annealing at high dose not only activates the Si dopant through the interaction of the interstitial Si and Ga vacancies but also causes interstitial Si atoms to diffuse into deeper regions. CL spectroscopy is very sensitive to the implantation damage and can be used for optimization of ion implantation and annealing processes in \beta_{-\mathrm{Ga}_2 \mathrm{O}_3} .